1. Field of the Invention
This invention relates generally to the processing of organic or carbon containing materials and more particularly to the pyrolization of such materials.
2. Background Information
Methods for the pyrolysis (sometimes referred to as carbonization) of organic materials such as coal is widely known. Pyrolysis is generally the process of converting organic materials including wood chips, sawdust, coal, and straw into more useful products such as charcoal and fuel. In most cases pyrolysis is accomplished by heating the organic material to from about 500 degrees C to 1,500 degrees C. This leaves a solid carbonaceous residue known as char or, depending upon the material, charcoal and produces gaseous and liquid products. The gases produced include carbon monoxide and hydrogen. The liquids include water, various aromatics and heterocyclics.
There are a number of problems relating to known methods of pyrolysis. In most instances, one of the byproducts of pyrolysis are a variety of tars which are not useful and tend to clog the reactor. Because pyrolysis involves heating the organic material to relatively high temperatures, the process and equipment tend to be fairly expensive. The high cost of transporting raw materials are an additional problem for pyrolyzers which are not mobile.
The various problems relating to pyrolysis have been addressed with some success in a number of patented inventions. The following patents are illustrative of the types of processes and equipment which have been tried.
A method for converting carbon containing materials such as straw or sawdust into fuel is disclosed in the patent to Chittick (U.S. Pat. No. 4,421,524; Dec. 20, 1983). One part of this fairly complicated process includes a pyrolysis reactor. Two embodiments of the pyrolysis reactor are shown. One embodiment includes a vertical cylinder with a cellulose intake at the top and an ash and gas outlet at the bottom. The reactor is loaded for most of its length with charcoal. The cylinder is surrounded with a heating jacket that heats the charcoal to the reaction temperature and the cellulose is introduced into the top. There is a stirring rod which goes down through he middle of the reactor. Paddles attached to the rod stir the mixture when a wheel on the top of the reactor is turned. In a second embodiment, material is pumped up through the bottom of the reactor.
A two stage pyrolysis process of coal for producing liquid hydrocarbon fuels is disclosed in the patent to Graff (U.S. Pat. No. 4,778,585; Oct. 18, 1988). This process includes a two steps for pyrolysis of coal. Coal is introduced into a pretreater in which it is heated to between 280 degrees C and 370 degrees C at a pressure of from 1 to 100 atmospheres. The product is transferred to a pyrolyzer where it is heated to between 600 degrees C and 800 degrees C at a pressure of from 1 to 100 atmospheres. In both cases the material is described as being treated by passing a heated gas such as steam through a bed of the material.
Another method for producing fuel gas from organic material is disclosed in the patent to Fetters (U.S. Pat. No. 4,530,702; Jul. 23, 1985). Although there are a number of embodiments described in the patent, this invention generally includes a vertical cylinder which is open at the top and which has a screen across the bottom. The bottom of the cylinder above the screen is filled to about 2/3 full with charcoal pellets. These pellets may come from a third party source or from previous operation of the pyrolizer. The charcoal pellets are burned until the unit reaches operating temperature and then raw pellets are introduced from a hopper onto the top of the charcoal pellets. In one embodiment there is an exit tube beneath the screen through which ash and gases are pumped through a filter. The pump pulls air down through the top of the cylinder. There are other embodiments which are similar including one in which the air is pumped through the bottom of the cylinder and the gases are removed above the screen.
Although the above described inventions address problems relating to pyrolization, none of them solve a number of other problems. All of these processes provide for a relatively stable bed of material which leads to the buildup of tars and other unwanted materials and provides for poor material transport. In addition, the use of a static bed provides for a relatively small reaction area or zone.
The instant invention is a pyrolizer which is unique, original, and fills the need for a new and improved method of pyrolyzing organic materials. The pyrolizer of the instant invention provides energy efficiency which is unknown in the prior art. The pyrolizer of the instant invention also provides for material transport which is significantly improved over known prior art and for a much larger reaction area or zone. The pyrolizer of the instant invention is also mobile.
In many cases a producer or manufacturer requires or desires char or charcoal having a particular composition. For example, a manufacturer may desire char which has a low ash content, low moisture content, high volatile content, and a medium carbon content. Another manufacturer may desire char having a different composition such as high ash content, low moisture, very low volatile content, and very high carbon content.
The ideal pyrolizer affects pyrolysis in a manner which produces the greatest percentages of useful products. The ideal pyrolizer should also accomplish pyrolysis in the most energy efficient manner. The ideal pyrolizer should also create the largest possible reaction area or zone to promote the desired reactions. The ideal pyrolizer should also be mobile and provide for efficient transfer of material through the reactor. The ideal pyrolizer should be able to provide char or charcoal having various compositions or specifications and to provide these varying specifications with relative ease and high accuracy. The ideal pyrolizer should also be simple to operate, durable, compact, and inexpensive.